Intrinsically safe field maintenance tools are known. Such tools are highly useful in the process control and measurement industry to allow operators to conveniently communicate with and/or interrogate field devices in a given process installation. Examples of such process installations include petroleum, pharmaceutical, chemical, pulp and other processing installations. In such installations, the process control and measurement network may include tens or even hundreds of various field devices which periodically require maintenance to ensure that such devices are functioning properly and/or calibrated. Moreover, when one or more errors in the process control and measurement installation is detected, the use of an intrinsically safe handheld field maintenance tool allows technicians to quickly diagnose such errors in the field.
One such device is sold under the trade designation Model 275 HART® Communicator available from Fisher-Rosemount Systems, Inc., of Eden Prairie, Minn. HART® is a registered trademark of the HART® Communication Foundation. The Model 275 provides a host of important functions and capabilities and generally allows highly effective field maintenance.
Intrinsic Safety requirements are intended to guarantee that instrument operation or failure cannot cause ignition if the instrument is properly installed in an environment that contains explosive gasses. This is accomplished by limiting the maximum energy stored in the transmitter in a worst case failure situation. Excessive energy discharge may lead to sparking or excessive heat which could ignite an explosive environment in which the transmitter may be operating.
Examples of intrinsic safety standards include European CENELEC standards EN50014 and 50020, Factory Mutual Standard FM3610, the Canadian Standard Association, the British Approval Service for Electrical Equipment in Flammable Atmospheres, the Japanese Industrial Standard, and the Standards Association of Australia.
In order to ensure stringent compliance with automation industry safety protocols and specifications, only equipment certified by an independent agency can be used in such locations. Any component of a handheld field maintenance tool which is removable must be replaced with another component that also satisfies all requisite safety requirements.
Another difficulty for modern intrinsically safe handheld field maintenance tools is that such tools can be provided with varying levels of functionality. Often times this functionality is controlled by software selections that are generated based upon a user purchasing specific groups of functionality. Since electric removable storage media usable with such devices is inherently portable, it is important to ensure that handling of these memory devices is performed in a manner that will not adversely affect the memory. Further, it is important to ensure that where the memory is removable from the handheld device, that even if there is no memory coupled to the handheld device, that intrinsic safety requirements can still be met.